Solutions of hydrogen peroxide are widely used in various commercial applications, such as processes for bleaching, cleaning, disinfection, sterilization and oxidation. In most applications diluted solutions are used, normally containing from about 0.1 to about 20 wt % of hydrogen peroxide. In many cases the hydrogen peroxide is present in a formulation together with other additives, such as surfactants or the like. However, for practical and economic reasons it is desirable to produce and transport hydrogen peroxide as more concentrated solutions, generally containing from about 30 to about 80 wt % of hydrogen peroxide, which solutions can be diluted on site to a desired concentration.
Hydrogen peroxide is sensitive to impurities catalyzing its decompositions, particularly heavy metal ions, but also some organic substances. Therefore, small amounts of stabilizers are normally added to the hydrogen peroxide by the manufacturer to inhibit its decomposition. It has, however, been found that under certain conditions even hydrogen peroxide solutions containing stabilizers do not have satisfactory stability, particularly those prepared by dilution of more concentrated solutions.
U.S. Pat. Nos. 3,122,417 and 4,304,762 disclose use of certain phosphonic acids for stabilizing hydrogen peroxide. It is not recommended to add too high levels of phosphonic acids as it increases the costs and tends to give reduced activity of the hydrogen peroxide.
U.S. Pat. No. 4,070,442 teaches that in order to stabilize hydrogen peroxide in the presence of high concentrations of heavy metal ions it is necessary to add both an alkylidene di-phosphonic acid and an organic hydroxy compound.